pyroclastic flow

A fast-moving cloud of superheated volcanic gasses, ash, and rock that hug the ground and even the surface of the sea as they rush at speeds of up to 450 mph, destroying anything in their paths. Pyroclastic flows are usually the result of centuries of pent-up stress within the volcano; thick, sticky magma plugs the vent of the volcano and thus builds greater and greater pressure until it explodes. Usually the flow is denser than the surrounding air and instead of flowing vertically, they rush along the ground, sweeping over hills and ridges like the said hills and ridges don't even exist. Pyroclastic flows can reach temperatures as high as 1830 degrees F, and the average temperature is about half that; hot enough to boil the blood in one's body and effectively flash-cook you alive. Some victims are charred while others get fatal steam burns. In short, a far more forceful and dangerous force than lava and more difficult to escape, due to their speed and intense heat.